Synthesis And Properties Of Hierarchically Nanostructured Materials Containing Titanium

Hierarchically nanostructured materials are built of nano-sized blocks,they not only possess the special properties of nanomaterials,but also have the unique characteristic due to the synergistic effect among the nano-sized block.Therefore,hierarchically nanostructured materialshave significant applicationsand research value in the area of light,electricity,magnetism and catalysis.The strategy to preparehierarchically nanostructured materialsmainly includes the template method and the non-template method.Template method can be divided into the soft-template method and the hard-template method.The mechanisms of non-template method are Ostwald ripping,Kirkendan effect andOriented attachment.Most of these methods are bottom-up and with two steps,the first step is the formation of nano-sized blocks.secondly,the final product is assembled by these blocks.On the basis of the previous work of our group,We expect that the promising titanium-containing hierarchically nanostructured materials including TiO₂ and Na₂Ti₃O₇can be synthesized from a top-down way with a topotactic transformation and solid-phase method.The method is characterized in:The precursor with specific macroscopic morphology is prepared.Then,the internal structure and composition of the final product are constructed through a solid-phase reaction without changing the external morphology of the material.This strategy is very simple,and the as-prepared product has a controllable external morphology and internal structures.In this paper,basic research on the synthesis and applications of TiO₂hierarchically nanostructured materialsmainly includes:1)?NH₄?₂TiOF₄ crystals precursors were synthesisedfrom ammonium fluorotitanate?NH₄?₂TiF₆)and ammonia?NH₄OH?.The influence of concentration ratio of the reactants,reaction temperature,surfactants on the composition and morphology of the product were investigated;2)As a precursor,?NH₄?₂TiOF₄was converted to TiO₂ composed of nano-particles by high temperature successivetopotactic transformation.The influence of calcination time,calcination temperature and calcinations method on the composition and morphology of the product were also explored;3)The effects of various reaction conditions on the photocatalytic activity of TiO₂ were studied;4)The TiO₂/MWCNT composite film was synthsised by vacuum suction filtration method.Its photocatalytic activity,antibacterial capability were tested.In this paper,basic research on the synthesis and applications of Na₂Ti₃O₇hierarchicallynanostructuredmaterialsmainlyincludes:1)The?NH₄?_xNa_yTi_zO?F_x+y+4z-2?precursor was synthesized from ammonium fluorotitanate??NH₄?₂TiF₆?,sodium polyacrylamide?Na-CPAM?and ammonia?NH₄OH?;2)The precursor was annealed to uniform hollow octahedral Na₂Ti₃O₇ composed of nano-particles.The influence of calcinations method,calcination time and calcination temperature on the composition and morphology of the products were also studied;3)The obtainedhierarchically nanostructuredNa₂Ti₃O₇ material as an anode material was assembled into a battery and its electrochemical properties were investigated.